1. Field of the Invention
The invention relates to a liquid crystal module including a structure of flexible substrates (which are each called a “tape carrier”) on which, for example, semiconductor chips and passive components for driving liquid crystal display (LCD) devices are mounted, and LCD devices.
2. Description of Related Art
With widespread use of cellular mobile phones in recent few years, rapid progress has been achieved in the aspect of their functionality with high added value or significant benefits. In addition to the aspects of software functions, such as motion-picture playback functions and Internet connection functions, significant advance has been accomplished also in the aspects of hardware functions such as those of camera functions. Among these functions, mainstreams are not only main LCD devices mainly for using, for example, conventional telephone functions and Internet functions, but also are cellular mobile phones concurrently having a subordinate LCD device for use of, for example, incoming-information guide display of mail, telephone, and the like data, communication status display, and residual battery capacity display.
Conventionally, the main LCD device and the subordinate LCD device are constituted as independent devices. As liquid crystal modules electrically connected to mutually different flexible substrates on which eigen liquid crystal drivers are mounted, the independent LCD devices are mounted in a single package in such a manner that their rear faces are mutually opposite and are driven independently of each other to perform display.
This technique requires two different liquid crystal drivers, namely, a liquid crystal driver for driving the main LCD device and a liquid crystal driver for driving the subordinate LCD device. Generally, the main LCD device and the subordinate LCD device are stored back to back in a package of a cellular mobile phone, there takes place a thinning limit.
By way of an improved technique for the above, FIGS. 8 and 9 show a liquid crystal module conventionally proposed. The module is configured to include a liquid crystal driver 4 formed by incorporating the functions of two liquid crystal drivers, and an end portion of a flexible substrate 3a on which the liquid crystal driver 4 is mounted and a main LCD device 1 are electrically connected together. On the side opposite a connection section of the main LCD device 1, the main LCD device 1 and a subordinate LCD device 2 are electrically connected together via a flexible substrate 7 formed only of wiring. The module is thus configured to aim for reducing the number of components and reducing the thickness. Another proposed liquid crystal module is configured to include a main LCD device and a subordinate LCD device on a common liquid crystal glass plate in lieu of the flexible substrate 7, and wiring is formed on the glass plate. In this configuration, the power is supplied from a terminal portion (not shown) of the flexible substrate 3a on which the liquid crystal driver is mounted, which terminal is formed on the side opposite an end portion of connection with the main LCD device 1.
In the conventional liquid crystal module, while segment wiring 5a is shared between the main LCD device 1 and the subordinate LCD device 2, common wiring 5b is not shared therebetween. As such, the common wiring is formed in two end portions on base glass 1b of the main LCD device 1, and is connected to the subordinate LCD device 2 via the flexible substrate 7 that connects between the main LCD device 1 and the subordinate LCD device 2.
As such, problems arise in that the configuration requires an edge region for forming the common wiring of the subordinate LCD device in two end portions of the base glass of the main LCD device, so that further miniaturization of the main LCD device is restrained. (Refer to Japanese Unexamined Patent Publication No. 2001-215475).